This application claims the benefit of German patent application 100 45 918.8 filed Sep. 16, 2000, herein incorporated by reference and German patent application 101 29 132.9 filed Jun. 16, 2001.
The present invention relates to an open-end spinning arrangement and, more particularly, to an open-end spinning arrangement having a stationary spinning box housing arranged on the base frame of a textile machine for seating a high speed spinning rotor in a vacuum-charged rotor housing, having a sliver opening unit connected to the spinning box housing via a linear guide, and having a cover element for closing the rotor housing.
Various embodiments of open-end spinning arrangements are known in connection with rotor spinning machines.
For example, German Patent Publication DE 43 23 213 A1 describes an open-end spinning arrangement with a support frame which has been fixed in place on the machine base frame of a spinning machine. The support frame has a support disk seating arrangement, an axial bearing, as well as a rotor housing, which can be closed by means of a pivotably seated cover element.
In this open-end spinning arrangement, a so-called conduit plate, a sliver draw-in cylinder, an opening roller, and a single-piece fiber guide conduit are arranged in the cover element.
The drive for the opening roller is provided in a customary way by means of a tangential belt, while the sliver draw-in cylinder is connected via a worm gear with a drive shaft extending over the length of the machine.
In the closed state of the rotor housing, a so-called conduit plate adapter is arranged on the conduit plate and projects into the spinning rotor. The conduit plate adapter carries a yarn-draw off nozzle and the mouth of the fiber guide conduit, so that the individual fibers exiting the mouth of the fiber guide conduit are directly fed to the fiber slide surface of the spinning rotor arranged immediately adjacent the fiber guide conduit.
In the course of producing high-quality open-end yarns, it is necessary to meet defined conditions regarding the mutual arrangement of the spinning elements, for example their distance and/or their size. Therefore, the pivotable arrangement of the cover element results limits the minimum diameter of the usable spinning rotor.
Thus, even with the arrangement of the pivot axis of the cover element almost vertically below the rotor opening, such as is described in German Patent Publication DE 43 23 213 A1, and with the relatively shallow pivot range thereby achieved, the employment of very small spinning rotors, for example of a diameter of  less than 28 mm, in the known spinning arrangements is very problematical.
Therefore attempts have already been made in the past to construct open-end spinning machines whose rotor housing cannot be closed by means of a pivotably seated cover element, but which has a cover element which is connected via a linear guide device with a stationary part of the open-end spinning arrangements.
German Patent Publications DE-OS 23 27 347 and DE-OS 23 27 348 show and describe rotor spinning arrangements with such a linear guide.
As can be seen in particular from FIGS. 1 and 2 of the drawings of these patent applications, these open-end spinning arrangements each have a stationary bearing housing for receiving a spinning rotor revolving inside a rotor housing, as well as a cover element, which is connected with the stationary bearing housing to be displaceable by means of a linear guide.
Furthermore, as already known, a sliver draw-in cylinder, as well as an opening roller, are arranged inside the cover element.
In such arrangement, the drive of the opening roller and the sliver draw-in cylinder takes place via central drive mechanisms extending over the length of the machine and are arranged fixed in place in the area of the stationary spinning rotor bearing housing.
In the interest of the uniformity of the yarn count, the sliver draw-in cylinder in particular must be driven free of slippage. Therefore, the transfer of the drive energy from the stationary drive mechanisms extending over the length of the machine to the sliver feed and opening devices arranged in the displaceably seated cover element is overall quite complicated and elaborate.
Because of their relatively failure-prone construction as a whole, the above described open-end spinning arrangements were not well-received and have therefore not been accepted in practical use.
Open-end spinning arrangements are also known wherein a sliver opening roller driven by an individual motor and/or a sliver draw-in cylinder driven by an individual motor are each arranged within the pivotably seated cover element.
An open-end spinning arrangement designed in this manner is described in German Patent Publication DE 43 09 947 A1, for example.
However, in connection with the spinning arrangement in accordance with such German Patent Publication DE 43 09 947 A1 it is disadvantageous that the cover element is connected with the spinning rotor bearing housing by means of a relatively difficult-to-access pivot shaft which, as explained above, leads to a definite restriction of the minimum rotor diameter, as well as, for example, to difficulties in connection with possibly required repairs of these individual drives.
Thus, with these known spinning arrangements the sliver opening unit driven by the individual motor and the sliver draw-in cylinder driven by the individual motor, integrated into the cover element, are relatively difficult to remove.
In view of the above described state of the art, an object of the present invention is to provide an improved rotor spinning machine. A more particular object of the invention is to further increase the productivity of rotor spinning machines by means of raising the number of revolutions of the spinning rotor and also to assure that the spinning arrangements are easy to access and to repair when needed.
In accordance with the invention, this object is addressed by providing an open-end spinning arrangement which basically comprises a stationary spinning box housing adapted to be arranged on a base frame of a textile machine for seating a high speed spinning rotor in a vacuum-charged rotor housing, a sliver opening unit connected to the spinning box housing via a linear guide, and a cover element for closing the rotor housing. In accordance with the present invention, the sliver opening unit is connected releasably to a connecting bracket of the linear guide, and the sliver opening unit comprises an opening roller driven by an individual motor and a sliver draw-in cylinder driven by a step motor arranged inside the sliver opening unit.
Advantageously, the use of a linear guide for seating the sliver opening unit enables very small spinning rotors to be employed if needed.
In turn, the use of extremely small spinning rotors makes possible a considerable increase of the number of revolutions of the spinning rotor, while at the same time assuring that the conditions of compatibility required for producing high-quality yarn, for example in regard to the positioning of the conduit plate adapter of the cover element, can be exactly maintained.
In a preferred embodiment, a step motor is employed for driving the sliver draw-in cylinder, and the sliver opening roller is driven by an individual motor, which assures in a simple and cost-effective manner a uniform individual fiber feeding into the spinning rotor, and thereby assures the exact uniformity of the yarn count at any time during the spinning process.
Furthermore, by means of an easily releasable connection of the sliver opening unit to the connecting bracket of the linear guide, it is furthermore assured that not only all components, for example the spinning rotor, remain easily accessible, but also that, when needed, the entire sliver opening unit can be replaced without problems, for example so that its individual drive mechanisms can be checked, and repaired in a special shop, if needed.
Thus, the preferred embodiment of open-end spinning arrangement in accordance with the present invention not only leads to a noticeable improvement of the productivity of such textile machines, but is also distinguished by ease of repair.
Furthermore, essential spinning components can be rapidly and dependably exchanged, for example in case of a batch change.
In one embodiment, the sliver opening unit is connected to the connecting bracket of the linear guide by means of a pivot shaft and is secured by means of a locking device.
In this manner, following the release of the locking device, the sliver opening unit can be tilted without problems via the pivot shaft, so that the greatest access to the spinning rotor, for example, is provided.
Since the pivot shaft is fixed in place in bearing slots which are open toward the front side of the arrangement, the sliver opening unit can also be removed without problems when needed and can be exchanged for another sliver opening unit, for example.
It is also advantageously provided that the locking device comprises a locking bolt, on which a spring force acts and which is displaceably seated on the connecting bracket of the linear guide, and a corresponding connecting bore is provided in the area of the sliver opening unit.
Thus, during the spinning operation, the sliver opening unit is pivoted inwardly to be dependably secured by means of latching of the locking bolt in the connecting bore and, at the same time, it is possible by means of retracting the locking bolt, which is preferably manually performed, that the locking device can easily be removed from service and the sliver opening unit can then be pivoted forward without problems and can be removed, if required.
It is further preferred that the sliver opening unit is connected with the connecting bracket of the first linear guide by means of a second, short linear guide.
In this manner, guide bolts may be arranged on the connecting bracket of this first linear guide, which slide in corresponding guide bores of a connecting body of the sliver opening unit.
The guide bolts in the present invention may each have an arresting groove in the area of their free ends, which can be engaged by a corresponding latching element.
These latching elements are preferably embodied as locking levers, which can be manually operated.
Thus, in the assembled state, two pivotably seated locking levers, which are biased by a spring element in an inwardly pivoted direction, engage the arresting grooves of the guide bolts and thereby interlockingly fix the sliver opening unit on the connecting bracket of the first linear guide.
In the present invention, the sliver draw-in cylinder, as well as the sliver opening roller, are driven by individual motors.
In a preferred embodiment, the sliver opening roller is driven by means of an individual electric motor drive, for example a d.c. or a.c. motor.
In this case this individual drive mechanism is embodied as a compact external rotor motor.
In an advantageous embodiment, a coupling device is arranged in the area of the connecting bracket of the first linear guide, which allows the mechanical separation of the electrical and pneumatic supply lines leading to the sliver opening unit.
In this manner, if required, the individual drive mechanisms arranged inside the sliver opening unit may be connected by supply lines, which can be easily separated, to an energy supply and control device arranged, for example, in the area of the stationary bearing device of the spinning rotor.
In a preferred embodiment, the coupling device comprises a coupling plate arranged on the connecting bracket of the first linear guide which, in the operating position of the open-end spinning arrangement, works together with a correspondingly embodied coupling element at the connecting body of the sliver opening unit.
Thus, a coupling element which, for example, is arranged in the area of the sliver opening unit, is embodied as a so-called xe2x80x9cmother elementxe2x80x9d, whose contact bushings are in contact with the individual drive mechanisms of the sliver opening unit.
In the locking position, contact pins which are arranged on the coupling plate, enter into these contact bushings and in this manner constitute an electrically and pneumatically continuous connection.
To assure the exact positioning of the sliver opening unit at any time, the connecting bracket of the first linear guide has a centering device on its rear side. Preferably, the centering device comprises two hardened fitting pins which, in the operating position, enter into corresponding centering bores of a stationary bearing block.
At least one of the centering elements of the centering device functions as a key switch. Thus, in the operating position of the sliver opening unit at least one of the fitting pins acts on an electrical switch such that this switch is kept in the closed position and therefore the supply line to the drive mechanisms of the sliver opening unit carries electrical current.
However, each relative movement between the sliver opening unit and the associated stationary bearing block immediately leads to the opening of the key switch and therefore to an interruption of the energy supply to the individual drive mechanisms.
Thus, the key switch assures in a simple manner that the releasable coupling device inserted into the supply lines for the individual drive mechanisms is always switched to be without electrical current or pressure prior to each separation.
Further details of the invention will be understood from the following description of an exemplary embodiment in conjunction with the accompanying drawings.